In their study, AA was added to stable doses of physiological hydrocortisone and 9α-fludrocortisone acetate to control androgen excess in 21OHD, and they proved that CYP17A1 inhibition is a good method to control androgen excess in classic 21OHD without using supraphysiological doses of hydrocortisone. Here, CYP17A1 is linked to hyperandrogenism.